In focused ion beam systems of the art, an ion beam is emitted from a source, accelerated, and focused into a small probe by ion optical lenses. The probe is scanned across a specimen by a deflector system. Such focused ion beam systems are used, for example, for imaging the specimen surface or for removing specimen material by sputtering. In this way, structures on the scale from several hundred microns down to a few hundred nanometers can be generated on the specimen.
Similarly, electron beam devices allow examining and/or manipulating of a specimen. For this purpose, electron beam apparatuses are known in the art, e.g., for electron microscopy. Such electron beam apparatuses include scanning electron microscopes, scanning transmission electron microscopes and the like.
The emitted charged particle beam, also known as the primary charged particle beam, can be tilted or deflected.
When the focused primary charged particle beam impinges on the specimen surface, the primary charged particles interact with the specimen and are either scattered or backscattered or generate secondary charged particles which originate from the specimen. For the purpose of this description any charged particles emerging after an interaction of the primary charged particle beam with the specimen are referred to as charged signal particles. Because the charged signal particles are generated upon interaction of the primary charged particles with the specimen, the charged signal particles transmit information about the specimen. For example, charged signal particles are primary charged particles which are backscattered from or transmitted through and scattered by the specimen. Moreover, so-called secondary charged particles, which are generated upon interaction of the primary charged particles with the specimen, are also referred to as charged signal particles. Secondary charged particles are for instance secondary electrons.
The charged signal particles are detected by appropriate particle detectors such as scintillators or the like to generate a detection signal. The detection signal can be used for various purposes. If, for example, the primary beam is used for manipulating the specimen, e.g., in ion milling applications, the detected charged signal particles allow for obtaining an image and/or a feedback signal for the manipulation process. In the case of scanning microscopy, a scanning image of the specimen is generated from the detection signal.
Charged particle apparatuses known in the art are described, for example, in the following documents: U.S. 2002/0079463 describes a sample fabricating method of irradiating a sample with a focused ion beam at an incident angle less than 90 degrees with respect to the surface of the sample. U.S. 2003/0209667 describes a beam directing method and device for spatially separating between a primary charged particle beam and a beam of secondary particles. U.S. 2003/0010913 describes a detector for scanning electron microscopes with high pressure in the sample chamber. U.S. Pat. No. 6,497,194 describes particle beam systems that include a work stage assembly and a first particle beam source. WO 01/45136 describes a method for the examination of specimen with a beam of charged particles that provides one or more images of the specimen made with different view angles.
However, the apparatuses of the art only provide for limited control possibilities of the primary charged particle beam or of the charged signal particles.